Harry K. Kaya

Pathogenicity of Pleistophora schubergi to larvae of the orange-striped oakworm and other lepidopterous insects

Abstract First- to fourth-instar larvae of the orange-striped oakworm, Anisota senatoria, are highly susceptible to infection by Pleistophora schubergi. Death of the oakworm usually occurs in the next instar following spore ingestion. P. schubergi infects a number of other forest lepidopterous insects.

Survival of spores of Vairimorpha (=Nosema) necatrix (Microsporida: Nosematidae) exposed to sunlight, ultraviolet radiation, and high temperature

Abstract Vairimorpha (=Nosema) necatrix spores sprayed on the upper surfaces of bean leaves and exposed to sunlight lost infectivity rapidly after 24 hr of exposure and were completely inactivated by 78 hr. When the uv protectant, Shade, was added to the spore suspension at 1% (w/v) concentration and sprayed onto leaves, spores retained infectivity for 30–48 hr without an appreciable loss, after which spores lost infectivity. Spores not exposed to sunlight retained a high degree of infectivity up to 120 hr. In laboratory tests, short (254 nm) uv radiation was detrimental to spores suspended in water. Exposure times of 4–10 min completely inactivated the spores. Spores on bean leaves exposed to short uv radiation were not completely inactivated even after 360 min. On the other hand, long (366 nm) uv radiation had no detrimental effect on spores suspended in water up to 360 min of exposure. Exposure of spores on bean leaves held in the dark at 35°C affected infectivity at 144 hr, but no effect was noted for spores held at 25°C.

Persistence of spores of Pleistophora schubergi (Cnidospora: Microsporida) in the field, and their application in microbial control

Abstract Spores of Pleistophora schubergi , when applied to oak trees in the field at 2 × 10 8 spores/ml with a uv protectant, “Shade,” infected 88% of Anisota senatoria larvae at 4 days after spray application. Spores without the uv protectant infected only 10% of the larvae at 4 days after application. When the spores were applied at the rate of 2 × 10 8 and 2 × 10 7 spores/ml in the field, 96 and 72% of the A. senatoria larvae and 100 and 100% of the Symmerista canicosta larvae were infected 14 days after spray application.